When building onto or modifying an existing building or property it is often necessary to cut into the existing wall structures to create new openings or to connect with an existing cavity. In these situations the cut edges must remain straight and must be in the correct position and plane. This is usually achieved using a powered disc cutter which is free cut by hand and there is difficultly in achieving a straight and accurate cut. Additionally, this process is required to be done with water acting as a dust suppressant making it difficult to follow markings made on the wall.
The wall may be, for example, any partition or boundary in the construction of a building formed from masonry including concrete block, facing bricks or natural stone, usually with an inner and outer wall and a cavity.